U.S. patent number 7,748,749 [Application Number 11/548,106] was granted by the patent office on 2010-07-06 for decoupling element impervious to liquid fluids.
This patent grant is currently assigned to Westfalia Metallschlauchtechnik GmbH & Co. KG. Invention is credited to Dietmar Baumhoff, Frank Bender, Stefan Hauk, Karl-Heinz Munker, Matthias Weiss.
United States Patent |
7,748,749 |
Baumhoff , et al. |
July 6, 2010 |
Decoupling element impervious to liquid fluids
Abstract
For connection of pipelines which are subject to vibration, for
example pipelines in vehicle exhaust systems, a liquid-tight
decoupling element is used which includes a, e.g. multi-layer
wound, metal hose and a tube accommodated in coaxial relationship
inside or outside of the metal hose. A first axial fitting firmly
secures one end of the tube. The tube is sized to protrude into a
second axial fitting, regardless whether the metal hose is
completely compressed or completely stretched, to allow movement of
the tube in axial and torsional directions in relation to the
second axial fitting.
Inventors: |
Baumhoff; Dietmar (Siegen,
DE), Bender; Frank (Drolshagen, DE),
Munker; Karl-Heinz (Hilchenbach, DE), Hauk;
Stefan (Hilchenbach, DE), Weiss; Matthias
(Hilchenbach, DE) |
Assignee: |
Westfalia Metallschlauchtechnik
GmbH & Co. KG (Hilchenbach, DE)
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Family
ID: |
38138554 |
Appl.
No.: |
11/548,106 |
Filed: |
October 10, 2006 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20070132232 A1 |
Jun 14, 2007 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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60724413 |
Oct 7, 2005 |
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Current U.S.
Class: |
285/49;
285/145.5; 285/226; 138/121 |
Current CPC
Class: |
F01N
13/1816 (20130101); F16L 51/023 (20130101); F16L
27/1004 (20130101) |
Current International
Class: |
F16L
11/12 (20060101) |
Field of
Search: |
;285/144.1,145.4,145.5,148.3,223,226,227,228,235,236,237,298,299,300,301,302,49
;138/106,109,114,121,129,154 ;403/50,51 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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428 348 |
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Jul 1967 |
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CH |
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34 41 064 |
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May 1986 |
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DE |
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38 04 105 |
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Mar 1989 |
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DE |
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198 20 863 |
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Nov 1999 |
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DE |
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101 13 180 |
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Oct 2002 |
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DE |
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203 02 657 |
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Oct 2003 |
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DE |
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2113336 |
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Aug 1983 |
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GB |
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WO 2004059140 |
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Jul 2004 |
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WO |
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Primary Examiner: Hewitt; James M
Assistant Examiner: Ripley; Jay R
Attorney, Agent or Firm: Feiereisen; Henry M. Day; Ursula
B.
Parent Case Text
CROSS-REFERENCES TO RELATED APPLICATIONS
This application claims the benefit of prior filed U.S. provisional
Application No. 60/724,413, filed Oct. 7, 2005, pursuant to 35
U.S.C. 119(e), the disclosure of which is hereby incorporated
herein by reference.
Claims
What is claimed is:
1. A decoupling element, comprising: first and second axial
fittings; a multi-layer spiral-wound metal hose pervious to gas and
having terminal ends which are immovably connected to the first and
second fittings, respectively, while allowing the metal hose to
undergo a torsional movement; a tube in the form of a bellows
accommodated in coaxial relationship to the metal hose and having
one end immovably connected to one of the first and second fittings
and another end radially secured to the other one of the first and
second fittings without inhibiting a movement of the tube in axial
and torsional directions; and an annular element radially securing
the tube to the other one of the first and second axial fittings,
wherein the tube is movably mounted in the other one of the first
and second axial fittings by the annular element in such a way as
to render the decoupling element effectively liquid-tight, pervious
to gas, and capable to move in axial and torsional directions.
2. The decoupling element of claim 1, wherein the tube is
accommodated in coaxial relationship within the metal hose.
3. The decoupling element of claim 1, wherein the tube is
accommodated in coaxial relationship outside the metal hose.
4. The decoupling element of claim 1, wherein the tube is made of
metallic material.
5. The decoupling element of claim 1, wherein the tube comprises a
material selected from the group consisting of elastomer, glass
fiber reinforced material, silicate fiber reinforced material,
ceramic material, compound material, and composite material.
6. The decoupling element of claim 1, wherein the annular element
is made of metallic material.
7. The decoupling element of claim 1, wherein the annular element
comprises a material selected from the group consisting of
elastomer, glass fiber reinforced material, silicate fiber
reinforced material, ceramic material, compound material, and
composite material.
8. The decoupling element of claim 1, wherein the tube in the form
of a bellows defines corrugations extending in a plane oriented
perpendicular to a rotation axis.
9. The decoupling element of claim 1, wherein the tube in the form
of a bellows defines corrugations which extend helically about a
perimeter of the tube.
10. The decoupling element of claim 1, wherein the tube and the
metal hose demarcate a cylindrical cavity therebetween, and further
comprising a dampening element provided in the cylindrical cavity
to effectively prevent metallic contact between the tube and the
metal hose and resultant noise generation when vibrating.
11. The decoupling element of claim 10, wherein the dampening
element is a metal braiding.
12. The decoupling element of claim 1, wherein the other one of the
first and second axial fittings has a circumferential cavity in the
form of a bead to collect liquid.
13. The decoupling element of claim 12, wherein the circumferential
cavity prevents a migration of liquid past the annular element to
an area of the metal hose, when the decoupling element is installed
horizontally.
14. The decoupling element of claim 1, wherein the tube is a metal
bellows.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a decoupling element for pipelines
subject to vibration. A typical example of an application would be
in vehicle exhaust systems.
Nothing in the following discussion of the state of the art is to
be construed as an admission of prior art.
Such devices are intended to connect in a flexible way pipes which
are subject to vibration, and to protect them from vibration. In
order to meet the requirements of the automotive industry
(passenger cars) for gas-tightness, a metal bellows is often a
module of such decoupling elements. As the large variations in
diameter in the corrugations of the metal bellows may lead to
turbulence, a metal hose is usually incorporated into the pipe so
as to ensure laminar gas flow. It must be ensured that any noise
generated during operation resulting from the metal hose hitting
the inside of the bellows is kept to a minimum. This is often
achieved by surrounding the hose with braiding. German
Offenlegungsschrift DE 198 20 863 A 1 shows a flexible pipe as an
example. Instead of using braiding, the metal hose and the metal
bellows are connected at defined points so as to prevent the
development of the type of noise described above.
For commercial vehicles, multi-layer wound metal hoses produced
from profiled strip material are frequently used as decoupling
element in exhaust systems. Since a low degree of leakage is
permissible, it is not necessary to use a gas-tight element such as
a metal bellows. A simple example of metal hoses used as decoupling
elements is the so-called Agraff hose. Further examples, which have
a longer service life and a lower leakage rate than Agraff hoses,
have been described in German publications DE 34 41 064 C2 and DE
101 13 180 C2.
Wound metal hoses are especially suitable for the exhaust systems
of commercial vehicles as they tolerate large offsets in the axial,
lateral, and above all the torsional direction without structural
tension arising. Their disadvantage, however, is the residual
leakage.
As legal provisions worldwide will be stipulating a substantially
reduced emission of pollutants from commercial vehicles, exhaust
systems will increasingly be fitted with exhaust gas treatment
modules such as soot filters and SCR systems. SCR systems in
particular place new technical requirements on decoupling elements
as they reduce nitrogen oxide in exhaust gas by adding AdBlue
(=urea). AdBlue is injected into the exhaust gas flow. Depending on
the service and ambient conditions, condensate may be formed on the
inside walls of the exhaust system. Liquid urea has a good seepage
ability and must not emerge from the exhaust system into the
environment. For this reason, all pipes used in the exhaust system
and in particular decoupling elements must be at least
liquid-tight.
It would therefore be desirable and advantageous to provide an
improved liquid-tight decoupling element to obviate prior art
shortcomings and to prevent any penetration of condensate urea into
the environment so as to be usable in exhaust systems in connection
with SCR systems, while still allowing substantial movements in
axial and in particular torsional direction.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, a liquid-tight
decoupling element includes a metal hose, a tube accommodated in
coaxial relationship to the metal hose, a first axial fitting for
firm connection of one end of the tube, and a second axial fitting
for radially securing another end of the tube to allow movement of
the tube in axial and torsional directions.
According to another feature of the present invention, the tube may
be accommodated in coaxial relationship within or outside the metal
hose.
According to another feature of the present invention, the tube may
be sized to protrude in the second axial fitting, regardless
whether the metal hose is completely compressed or completely
stretched.
According to another feature of the present invention, an annular
element may be provided for radially securing the tube to the
second axial fitting. The tube may hereby be movably mounted in the
second axial fitting by the annular element, regardless whether the
metal hose is completely compressed or completely stretched.
According to another feature of the present invention, the tube may
be made of metallic material with a defined mechanical feature and
a defined chemical composition. As an alternative, the tube may
also be made of elastomer, glass fiber reinforced material,
silicate fiber reinforced material, ceramic material, compound
material, or composite material. Likewise the annular element may
be made of metallic material with a defined mechanical feature and
a defined chemical composition, or of elastomer, glass fiber
reinforced material, silicate fiber reinforced material, ceramic
material, compound material, or composite material.
According to another feature of the present invention, the tube may
be rigid with a high stiffness.
According to another feature of the present invention, the tube may
be flexible.
According to another feature of the present invention, the tube may
have a bellows-type geometry to define corrugations extending in
two planes oriented perpendicular to one another in orthogonal
relationship to a rotation axis, or with corrugations which extend
helically about a perimeter of the tube.
According to another feature of the present invention, the tube and
the metal hose may demarcate a cylindrical cavity therebetween for
receiving a dampening element to effectively prevent metallic
contact between the tube and the metal hose and resultant noise
generation when vibrating. Suitably, the dampening element is a
metal braiding.
When using a liquid-tight decoupling element according to the
present invention in an exhaust system of a motor vehicle, the
second axial fitting may have a circumferential cavity in the form
of a bead to collect liquid contained in the exhaust system. The
circumferential cavity prevents hereby a migration of liquid past
the annular element to an area of the metal hose, especially when
the decoupling element is installed horizontally.
According to another feature of the present invention, the tube may
be a multi-layer wound corrugated tube.
According to another feature of the present invention, the tube may
be a corrugated tube produced by partial expansion of a tube.
According to another feature of the present invention, the tube may
be a metal bellows.
According to another feature of the present invention, the metal
hose may be a multi-layer wound metal hose.
According to another feature of the present invention, the metal
hose may be connected to the axial fittings.
BRIEF DESCRIPTION OF THE DRAWING
Other features and advantages of the present invention will be more
readily apparent upon reading the following description of
currently preferred exemplified embodiments of the invention with
reference to the accompanying drawing, in which:
FIG. 1 is a schematic illustration of one embodiment of a
decoupling element according to the present invention;
FIG. 2 is a schematic illustration of another embodiment of a
decoupling element according to the present invention;
FIG. 3 is a schematic illustration of a modification of the
decoupling element of FIG. 1;
FIG. 4 is a schematic illustration of another modification of the
decoupling element of FIG. 1;
FIG. 5 is a schematic illustration of yet another embodiment of a
decoupling element according to the present invention;
FIG. 6 is a schematic illustration of still another embodiment of a
decoupling element according to the present invention; and
FIG. 7 is a schematic illustration of yet another embodiment of a
decoupling element according to the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Throughout all the Figures, same or corresponding elements are
generally indicated by same reference numerals. These depicted
embodiments are to be understood as illustrative of the invention
and not as limiting in any way. It should also be understood that
the drawings are not necessarily to scale and that the embodiments
are sometimes illustrated by graphic symbols, phantom lines,
diagrammatic representations and fragmentary views. In certain
instances, details which are not necessary for an understanding of
the present invention or which render other details difficult to
perceive may have been omitted.
Turning now to the drawing, and in particular to FIG. 1, there is
shown a schematic illustration of one embodiment of a decoupling
element according to the present invention, generally designated by
reference numeral 1. The decoupling element 1 includes a wound hose
11 which is produced by thread-type multi-layer winding of profiled
metallic strip material. Accommodated in the wound hose 11 in
coaxial relationship is a flexible metal tube 12 which is firmly
connected on a left-hand side with an axial fitting 17 by a
material union or in a form-fitting manner. As an alternative, as
shown in FIG. 7, the tube 12 is accommodated in coaxial
relationship outside the metal hose 11. The metal tube 12 may, e.g.
be realized in the form of a multi-layer wound corrugated tube, a
corrugated tube 401 shown in FIG. 6 and produced by partially
expanding a tube, or a metal bellows 201, as shown by way of
example in FIG. 4. Although the flexible tube 12 is described here
as being made of a metal material, it is also possible to make the
flexible tube of elastomer, glass fiber reinforced material,
silicate fiber reinforced material, ceramic material, compound
material, or composite material.
A sleeve 15 is fitted between an outside diameter of the flexible
metal tube 12 and an inside diameter of the wound hose 11 to define
a cylindrical cavity 19 between the flexible metal tube 12 and the
wound hose 11. A dampening element 301, as shown in FIG. 5, such as
braiding, may be placed in the annular cavity 19 to effectively
prevent metallic contact between the flexible metal tube 12 and the
wound hose 11 and thus any noise generation when the decoupling
element 1 vibrates. A sleeve 13 is placed over the left-hand end of
the wound hose 11 and connected to the hose 11 by a material union
or in a form-fitting manner.
On the right-hand side, the decoupling element 1 includes an axial
fitting 18 by which the wound hose 11 is connected with a second
sleeve 14 by a material union or in a form-fitting manner. For
reasons of fatigue strength, the flexible tube 12 cannot be firmly
connected with the fitting 18. Rather, an annular element 16 is
used to realize an attachment which secures the flexible tube 12
radially in the fitting 18, while allowing the flexible tube 12 to
move in axial and torsional directions. This ensures that the
flexible tube 12 needs only to absorb lateral movements during
operation. The absence of axial and torsional loads as a
consequence of the design has a positive influence on the fatigue
strength of the flexible tube 12. Care must be taken however that
the annular element 16 is accommodated inside the right fitting 18,
even when the wound hose 11 is fully stretched or extended.
As shown in FIG. 3, the fitting 18 may also be provided with a
circumferential cavity 101 in the form of a bead to collect any
liquid present in the exhaust system and to ensure, particularly
when installed horizontally, that no liquid may pass the annular
element 16 and migrate to the area of the wound hose 11 against the
direction of flow.
The decoupling element 1 is liquid-tight when exhaust gas flows
from the left fitting 17 to the right fitting 18. Any residual
leakage refers solely to gas and is determined by the sealing
effect of the annular element 16 and tightness of the wound hose
11. As different geometries of the wound hose 11 lead to different
leakage rates, any residual leakage can be influenced through
suitable construction of the wound hose 11 with lay-on profile,
Agraff hoses or hose sections according to the afore-mentioned
German publications DE 344 1064 C2 and DE 101 13 180 C2.
The decoupling element 1 is designed particularly for decoupling in
the axial and torsional directions. Lateral flexibility is
determined by the size of the cylindrical cavity 19 and lateral
stiffness of the flexible tube 12. By varying these two elements,
different designs are possible. For example, a decoupling element,
which is intended exclusively for axial and torsional decoupling,
may be provided with a very small cylindrical cavity 19 and a rigid
tube 12. If greater lateral flexibility is required, the
cylindrical cavity 19 must be sufficiently large, and the flexible
tube 12 should have a low lateral stiffness.
Referring now to FIG. 2, there is shown an alternative arrangement
of a decoupling element, generally designated by reference numeral
10. Parts corresponding with those in FIG. 1 are denoted by
identical reference numerals and not explained again. The
description below will center on the differences between the
embodiments. In this embodiment, provision is made for a tube 21
having a staggered diameter.
The annular element 16 can be made of pressed metal braiding. As an
alternative, the annular element 16 may be made from ceramic, glass
fiber reinforced material, silicate fiber reinforced material or
composite material. These materials may also be used to fill the
cylindrical cavity 19.
To suit a decoupling element according to the invention to a
special application, combinations of the above designs are, of
course, possible. In addition to its use in vehicle exhaust
systems, the liquid-tight decoupling element described is also
suitable for industrial applications such as the exhaust systems of
stationary turbines.
While the invention has been illustrated and described in
connection with currently preferred embodiments shown and described
in detail, it is not intended to be limited to the details shown
since various modifications and structural changes may be made
without departing in any way from the spirit of the present
invention. The embodiments were chosen and described in order to
best explain the principles of the invention and practical
application to thereby enable a person skilled in the art to best
utilize the invention and various embodiments with various
modifications as are suited to the particular use contemplated.
What is claimed as new and desired to be protected by Letters
Patent is set forth in the appended claims and includes equivalents
of the elements recited therein:
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